a) Field of the Invention
The invention is directed to a device for holding optical components, particularly light guides, in which the light is guided at the outer surfaces of the light guides by total reflection. Light guides of this type are known in essentially two embodiment forms: as cylindrical light guides, e.g., light-conducting fibers, and as prismatic light guides, e.g., light mixing rods, as they are called, such as those used in modern digital projection.
b) Description of the Related Art
A light mixing rod of the type mentioned above is known, e.g., from German Patent DE 198 19 246. It comprises a polygonal or prismatic body which is totally reflecting at the lateral surfaces. This reference also describes the difficulty presented by holding such mixing rods due to the fact that contact with the holder can inhibit total reflection in some areas and can accordingly result in light losses. As a solution to this problem, the reference proposes that the holder be realized as a punctiform or line-shaped support in order to minimize losses. In particular, it is suggested that the holder be constructed from very thin sheet metal which contacts the mixing rod only by an edge. However, the stability of a holder of this type is in need of improvement. Further, it has been shown that contamination of the outer surfaces of the mixing rod cause considerable losses.
In light-conducting fibers with a homogeneous distribution of the refractive index, the same problems occur on principle. Gradient index fibers in which the total reflection occurs inside the fiber and not at its interfaces or boundary surfaces due to a special inhomogeneous refractive index curve were developed as a remedy. However, fibers of this kind are much more complicated to produce than fibers of homogeneous material.